The recovery of rhodium, iridium, palladium and platinum from ores and concentrates by wet assay and a comparison with recovery by fire assays

Abstract

A wet method for recovering micro amounts of rhodium, iridium, palladium and platinum from ores and concentrates is reported. It involves stepwise dissolution of the roasted sulphide concentrate. The calcined material is leached with aqua regia or with concentrated hydrochloric acid followed by aqua regia. The leached residue is chlorinated, silicon is volatilised as silicon tetrafluoride from the chlorinated residue, and the final residue is fused with sodium peroxide. From the resulting solution the base metals are removed by a cation-exchange technique. A Chromatographic method followed by solvent-extraction procedures is used to separate the above four platinum metals from the effluent from the small cation exchanger. The efficiency of the method is compared with that of both the copper-nickel-iron and the classical (lead) fusion methods, applied to the same ore and concentrate.